The discovery of RNA interference (RNAi) may well be one of the transforming events in
biology in the past decade. RNAi can result in gene silencing or even in the expulsion of
sequences from the genome. Harnessed as an experimental tool, RNAi has revolutionized
approaches to decoding gene function. It also has the potential to be exploited
therapeutically, and clinical trials to test this possibility are already being planned.